Radio transmission apparatus



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Jan. 8, 1935. A, GEBHARD ET Al. 1,986,805

RADIO TRANSMISSION APPARATUS Filed April 8, 1933 C5 Sheets-Sheet l ATTORNEY Jan. 8, 1935. L A. GEBHARD ET AL RADIO TRANSMISSION APPARATUS Filed April 8, 1955 3 Sheets-Sheet 2 BY (b1/clef Jan. 8 1935. l.. A. GEBHARD ET AL I RADIO TRANSMISSION APPARATUS Filed April 8, 1953 5 Sheets-Sheet 3 29% TE E INVENTOR f5 25 QOM/b a ffl/@661.0 a y zM/ 534W ATTORNEY BY @0x/cub Patented Jan. 8, 1935 RADIO TRANSMISSION APPARATUS Louis A. Gebhard and Corrie F. Rudolph, Washington, D. C.

Application April s, 1933, serial No. 665,183 15 claims.' (umso-17) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. '757) coupling inductances concentrically related therewith for insuring extremely short connection between the several circuit elements.

Another object of our invention is to provide a radio frequency unit for transmitters wherein the electron tube, balance condenser, adjustable inductance coil and coupling coil are all disposed on the same concentric axis in such compact arrangement as will insure short leads between the circuit elements for maintaining high operating efficiency.

A further object of our invention is to provide 4an arrangement for mounting a radio transmitter unit in a frame structure with adjusting devices extending through the frame` structure and engaging a balance condenser and tuning inductance concentricallyv disposed with respect to a fluid cooled electron tube and coupling coil compactly assembled for insuring minimum length of leads between the circuit units.

A still further object of our invention is to provide a push pull. amplifier unit comprising a frame having a pair of high power tubes mounted therein with balance condensers, tuning inductances and couplings coils individual to each of said tubes and concentrically related thereto with means extending through the frame for simultaneously adjusting the balance condensers and tuning lnductances for selected operating frequencies.

Another object of our invention is to provide a fluid cooled tuning inductance and electron tube unit concentrically related in a compact manner in association with a balance condenser and a coupling coil, each of which is concentrically disposed with respect to the electron tube unit with means for independently adjusting the balance condenser and tuning inductance for selected operating frequencies.

Other and further objects of our invention reside in the circuit arrangement for an amplifier system and the construction of an amplifier unit as will be more fully understood from the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a side elevation o'f the Aapparatus of our invention with parts broken away and shown partially in central vertical longitudinal section; Fig. 2 is a horizontal sectional view taken on line 2-2 of Fig. 1, parts being omitted to avoid confusion; Fig. 3 is a bottom plan view with parts broken away and shown in horizontal section; Fig. 4- is a transverse vertical view taken substantially on line 4 4 of Fig. 2; Fig. 5 is a schematic view showing our improved amplifier circuit; Fig. 6 is a plan view of the electrostatic shield which we provide between the coupling coil and inductance system in the balance condenser; Fig. 'l is a side elevationof the electrostatic shield illustrated in Fig. 6; and Fig. 8 is a cross sectional view taken through the electrostatic shield on line 8--8 of Fig. 8.y

In radio transmitters for operation on high frequencies and high power it is desirable that the circuit structure of the final amplier be as compact as possible. Compactness is necessary in order to provide satisfactory operation at high frequencies. There are factors however, which militate against compact design such as breakdown voltage requirements, covering a wide frequency band, reduction of losses, water cooling, etc. An arrangement having the desirable advantagesl without the disadvantages is described hereinafter.

Referring to the drawings in detail, an inductance, electron tube and a cooling fluid jacket arrangement 1, 6 and 3, respectively, are axially aligned with balance condenser 4 and coupling coil 5. The system may consist of a single unit or two units in a push-pull connection. Each unit includes an electron tube, tube jacket, balance condenser, tuning coil and coupling coil, all axially arranged in compact relation. The jacket, balance condenser, tuning coil and coupling coil are supported by vertical insulating members 7 which'are in turn supported from the framework 8 of the transmitter by means of horizontal insulating members 9 and 10. The coupling coils 5 are disposed between the balance condensers 4 and tuning coilsl. This arrangement places the coupling coil adjacent to the active, upper end of the tuning coil. The lower portion of the tuning coil is the part which is short circuited to provide selective tuning adjustment; The coupling coils may be connected in series as shown in Fig. 5 to feed a symmetrical antenna system 11 through coupling and transmission line adjustor 12 and transmission line 13 leading to the doublet antenna system 11. The tuning coils 1 are wound in the same direction to provide a minimum external field with maximum inductance. The

coupling coils 5 are wound in opposite directions so that when placed in parallel an unsymmetrical circuit may be fed while maintaining symmetrical coupling to the push-pull circuit. Thisis due to the particular directions of the winding of the coils which provides symmetrical magnetic and electric couplings. The electric coupling to both halves of the push-pull circuit is the same since the capacity between the common ends of the coupling coils and the high potential ends of the tuning coils is substantially the same.

The balance condensers 4 are arranged at the top of the group so that the connections 14 to the grids of the tubes 6 will be as short as possible. This permits greater accuracy of the balance. Cooling uid is introduced and discharged at 15 and 16 to cool the turns of coils 1 and 1 and tubes 6 and 6 by the parallel connection of the coils as shown. Controls 17 and 18 and indicators 19 and 20-are provided for the tuning coils 1 and balance condensers 4, respectively, as shown in Figs. 2 and 4.

The entire system is enclosed in a framework covered with suitable metallic shielding. The continuously variable input tuning coil 21 is electrically arranged in parallel with the top of the tubes for symmetrical, short grid and balance connections. This arrangement places this coil at right angles to the continuously variable output tuning coils- 1, minimizing coupling effects between these two circuits. It should be noted that one half, or one unit, of the system may be used for certain applications if it is so desired.

In order to insure against undesired electrostatic coupling between the balance condenser, tuning coil and coupling coil, we provide an electrostatic shield 25 shown more clearly in Figs. 6, 7 and 8. The electrostatic shield 25 is in the form of a split disc which is provided with a sleeve 25a which engages the exterior wall of the fluid cooled jacket of the electron tube as represented at 26. A suitable annular strap member 27 is provided to maintain the shield in position. The shield 25.

has a suicient thickness -to permit screws A28 to be secured therein in screw threaded apertures 28a, the screws 28 being passed through the lower extremity of the outside plate of the balance condenser 4. The electrostatic shield 25 forms a continuation of the outside plate of the balance condenser 4 and is maintained at such spacial relation from the inside plate of the balance condenser as to avoid any breakdown due to the proximity of the plate 25 of opposite potential. That is to say, the inside capacity area 29 of condenser 4 and the outside capacity area 30 of condenser 4 are maintained at predetermined spacial relation which is not destroyed by the interposition of the electrostatic shield 25. as the airgap 31 is maintained of a sucient length to prevent breakdown of the condenser. The electrostatic shield 25 does not constitute a closed conductor as a positive air-gap 25h is left in the electrostatic shield for avoiding losses which might otherwise arise in the electrostatic shield due to eddy currents in view of the close proximity of the shield to the tuning and coupling coils.

In order to avoid duplication in reference characters, We have employed prime reference characters to indicate corresponding parts in the duplicate electron tube systems of a symmetrical transmission circuit.

It will be observed that the same insulating members 7 provide a unitary mounting means for the balance condenser, the coupling coil 5 and the turns of the coupling coil 5 and tuning coil 1.

There is a distinct difference betwen the mode of operation of the controls 17 and 18. Control 17 which projects from the front of the panel of the transmitting apparatus illustrated at 27 operates to drive a shaft which is broken by insulating coupling members 31 and 32 for driving worms 33 and 33' which mesh with worm wheels 34 and v 34 respectively. Worm wheels 34 and 34 are mounted Aon cylinders 35 and 35' respectively,

which cylinders form a resilient connection with the upper portion of spiral rack members 36 and 36 which are centered in the lower ends of the fluid cooled jackets 26 and 26. Radially extending contactors 37 and 37' having a radially projecting pin 37a projects through the slot 35a in cylindrical member 35 for enabling the contactor 37 to be driven up and down the spiral rack 36 for adjusting the position of the contactor on the turns of the inductance l. A similar slidable adjustment is provided on the other tuning coil 1'. It will be observed that worms 33 and 33 are pitched in the same direction to produce simultaneous movement of worm wheels 34 and 34' for adjusting the contactors up and down the tuning inductances. The cooling fluid which is introduced and discharged at 16 circulates through the turns of the inductance 1 and through the spiral rack 36 and 36' and through the central tube 38 and 38' to the fluid cooling jacket 26 and between the concentric walls in the space 40 thereof for maintaining thev electron tube mounted in thejacket cooled during the entire period of operation thereof.

The control 18 for the balance condensers does not operate upon the same principle as that upon which control 17 functions. The balanc condensers are driven in opposite directions and hence it is necessary that the control shaft 18 impart movement to the inner capacity area 29 in a direction opposite to that in which inner capacity area 29"is accomplished. This is accomplished by extending the control shaft through insulated supports 7 and 7' as indicated with coupling insulators 41 and 42 interposed in the shaft and with worm wheels 43 and 43 driven by the shaft oppositely pitched. Worm wheel 43 is pitched in a direction opposite the worm wheel 43. When movement is imparted by worm wheel 43 to the movable cylindrical eleme i". of the intercapacity area 29 of the balance condenser, the movable cylindrical element as represented in Fig. 2 moves in a counterclockwise direction for increasing the total'capacity of the balance condenser 4. At the same time worm wheel 43 which is oppositely pitched engages the movable element of the intercapacity area 29 of balance condenser 4 and advances the movable element in a clockwise direction, thus increasing the capacity of balance condenser 4. That is to say, the balance condensers are simultaneously increased and decreased in effective capacity 1lthough the movable elements are driven in opposite directions. While control 17 operates to drive the movable elements in the same direction, control 18 operates to drive the movable elements in opposite directions and yet the capacity is increased and decreased simultaneously in the symmetrical electron tube circuits. l

The electrically shielded construction of the electron tube jacket, balance condenser, coupling coil Aand. tuning coil insures the eilicient operation of the several elements in the circuit while permitting the grouping of the elements in compact relation. We realize that various forms of shielding maybe employed and while we have described our invention in certain preferred embodiments, we desire that it be understood that modications may be made and that no limitations are intended upon our invention other than are imposed by the scope of the appended claims.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalty thereon or therefor.

What we claim as new and desire to secure by Letters Patent of the United States is as follows:

i l. Transmission apparatus comprising a frame structure, a `multiplicity of insulating members vertically disposed in said frame structure, 'a iluid cooled electron tube support carried by one end of said frame structure, a balance condenser concentrically mountedv about said fluid cooled tube support, means for supporting said balance condenser from said insulating members, a tubular conductor tuning coil having its turns mounted in spacial relation and supported by said insulating members, means extending through said insulating members axially of said tuning coil for adjusting the effectivevnumber of turns in said tuning coil, and means adjacent the aforesaid means for distributng cooling fluid through the tubular conductors of said tuning coil and through said uid cooled electron tube support.

2. Transmission apparatus comprising a frame structure, a multiplicity of insulating members vertically disposed in said frame structure, a fluid cooled electron tube support carried by one end of said frame structure, a balance condenser concentrically mounted about said fluid cooled tube support, means for supporting said balance condenser from said insulating members, a tubular conductor tuning coil having its turns mounted in spacial relation and supported by said insulating members, means extending through said insulating members axially of said tuning'coil for adjusting the effective number of turns in said tuning coil, means adjacent the aforesaid` means for distributing cooling fluid through the tubular conductors of said tuning coil and through said fluid cooled electron tube support, and means for electrostatically isolating said balance condenser from said tuning coil.

3. Transmission apparatus comprising a frame structure, a multiplicityoi insulating members vertically disposed in sai'd frame structure, a fluid cooled electron tube support carried by one end of said frame structure, a balance condenser concentrically mounted about said fluid cooled tube support, means for supporting said balance condenser from vsaid insulating members, a tubular conductortuning coil having lits turns mounted in spacial relation and supported by said insulating members, means extending through said insulating members axially of said tuning coil for adjusting the eiective number ofturns in said tuning coil, means adjacent the aforesaid means for distributing cooling fluid through the tubular conductors of said tuning4 coil and through said fluid cooled electron tube support, and a laterally extending electrostatic shield interposed between said balance condenser and 'said tubular conductor tuning coil.

4. Transmission apparatus comprising a frame structure of insulating material, a fluid cooled structure of insulating material, a balance con- A denser supported in one end of said frame structure, an inductance supported in the other end of said frame structure. and an electrostatic shield disposed laterally of said frame structure and separating said balance condenser from said inductance, said electrostatic shield comprising a disc havingV a radial slot therein for decreasing any eddy current loss in said disc induced by the magnetic field of said inductance.

6. High frequency transmission apparatus comprising a frame structure of insulating material, a uid cooled electron tube jacket disposed axially of said frame structure, a balance condenser concentrically disposed about said fluid cooled electron tube jacket, an inductance having the' thereof supported by said frame` axially of saidframe structure, a balance con-A denser concentrically disposed about said fluid cooled electron tube jacket, an inductance having the turns thereof supportedby said frame structure of insulating material, and an electrostatic shield supported by said fluid cooled electron tube jacket and extendingl laterally of said balance condenser, said electrostatic shield being mechanically and electrically connected with one of the capacity areas of said balancecondenser and having a radial slot therein for substantially eliminating losses due to the setting up of eddy currents induced by the magnetic field from said inductance.

8. Transmission apparatus comprising a frame structure of insulating material, a balance condenser supported by said frame structure, a fluid cooled electron tube jacket supported by the upper end of said frame structure, said balance condenser concentrically disposed about said jacket, an inductance having the turns thereof supported by said frame structure beneath said balance condense", a coupling coil carried by said frame structure of insulating material in coupled relation to said inductance, and an electrostatic shield supported by said jacket and extending in a plane normal to the axis of said inductance and coupling coil and connected at its outer periphery with' one of the capacity areas of said balance condenser.

9. High frequency transmission apparatus -comprising a pair of symmetrical units, each of a coupling coil disposed in axial relation, means for mounting said units in parallel relation, and means for simultaneously controlling the effective number of turns in the inductances of each of said units.

10. High frequency transmission apparatus comprising a pair of symmetrical units, each of said units including an electron tube mounting device, a balance condenser, an inductance and a coupling coil disposed in axial relation, means for mounting said units in parallel relation, a rotary contactor engaging the turns of the inductance in each of said units, and means for simultaneously driving the rotary contactors in each of said units for controlling the effective number 'of turns in the said inductances.

11. High frequency transmission apparatus comprising a frame structure of insulating material including oppositely disposed vertically extending frame members, a unit comprising ay fluid cooled tube jacket, a concentrically disposed balance condenser supported in the upper portion of said frame structure, a tubular member extending axially of said frame structure for supplying and `discharging cooling fluid to said jacket, an inductance having the turns thereof supported in said oppositely disposed vertically extending frame members, a coupling coil having the turns thereof mounted in said oppositely disposed Vertically extending frame members, and an electrostatic shield supported by said uid cooled tube jacket and connected with one of the capacity areas of said balance condenser and extending `normal to said frame members.

12. High frequency transmission apparatus comprising a frame structure of insulating material including oppositely disposed vertically extending frame members, a unit comprising a fluid cooled tube jacket, a concentrically disposed balance condenser supported in the upper portion of said frame structure, a tubular member extending axially of said frame structure for supplying and discharging c'ooling fluid to said jacket, an inductance having the turns thereof supported in said oppositely disposed vertically extending frame members, a coupling coil having the turns thereof mounted in said oppositely disposed vertically extending frame members, and an electrostatic shield supported by said iiuid cooled tube jacket and connected with one of the capacity areas of said balance condenser and extending normal to said frame members, said electrostatic shield comprising a disc having a radially disposed slot to one side thereof for reducing eddy current losses due to the electromagnetic eld established by said inductance and said coupling coil.

13. High frequency transmission apparatus comprising a pair of symmetrical-units, each of said units including an electron tube mounting device, a balance condenser, an inductance and a coupling coil disposed in axial relation, means for mounting said units in parallel relation, means for simultaneously varying the effective capacities of the balancing condensers in said units, a rotary contactor engaging the turns of the inductance in each of said units, and means for simultaneously driving the rotary contactors in each of said units for controlling the eifective number of turns in the said inductances.

14. High frequency transmission apparatus comprising a pair of symmetrical units, each of said units including an electron tube mounting device, a balance condenser, an inductance and a coupling coil disposed in axial relation, means for mounting said units in parallel relation, means for simultaneously increasing or decreasing the effective capacities of the balancing condensers in said` units, means for simultaneously varying the eiective number of turns in the inductances in structure of insulating material, a iluid cooled electron tube mounting and a balance condenser concentrically supported in one end of said frame structure, an inductance formed of a tubular conductor adapted to convey cooling fluid. to and from said yelectron tube mounting supported in the other end of said frame structure, means for adjusting the effective capacity of said balance condenser, means for adjusting the effective number of turns in said inductance, a coupling coil disposed in magnetic relation with said inductance, and an electrostatic shield disposed laterally of said frame structure and separating said balance condenser from said inductance and said coupling coil. v

LOUIS A."GEBHARD.

CORRIE F. RUDOLPH. 

